packing density
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Some birds achieve primate-like levels of cognition, even though their brains tend to be much smaller in absolute size. This poses a fundamental problem in comparative and computational neuroscience, because small brains are expected to have a lower information-processing capacity. Using the isotropic fractionator to determine numbers of neurons in specific brain regions, here we show that the brains of parrots and songbirds contain on average twice as many neurons as primate brains of the same mass, indicating that avian brains have higher neuron packing densities than mammalian brains. Additionally, corvids and parrots have much higher proportions of brain neurons located in the pallial telencephalon compared with primates or other mammals and birds. Thus, large-brained parrots and corvids have forebrain neuron counts equal to or greater than primates with much larger brains. We suggest that the large numbers of neurons concentrated in high densities in the telencephalon substantially contribute to the neural basis of avian intelligence.
- MeSH
- mozek cytologie MeSH
- neurony * MeSH
- počet buněk MeSH
- primáti MeSH
- ptáci * MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Introduction: We studied influence of mud-bath on bone status in male Wistar rats with subchronic arthritis. Methods: Arthritis was induced by 2 subplantar injections of Freund's adjuvans with heat-killed Streptoccocus pyogenes into paw. Groups: intact (int) on chippings; (con) arthritis on chippings; (san38) arthritis on hot sand; (mu38) arthritis on hot mud; (mu21) arthritis on mild mud. Bone mineral density (BMD, g/cm2) was measured by dual energy X-ray absorptiometry and femurs were tested biomechanically. Bone markers osteocalcin (OC), PINP and CTX were analysed in bone. Results: BMD of right femur decreased vs. left in san38 (p = 0.030) and mu38 (p = 0.047). Fracture load of right/left femur (N) decreased in experimental groups, significantly in san38 (p = 0.05). Fracture threshold of neck decreased in right vs. left in experimental groups, but significantly in san38 (p = 0.05). OC decreased in mu38 vs. con (1.84 ± 0.14/2.62 ± 0.23). PINP decreased in int vs. san38 (p = 0.005) and mu21 (p < 0.001). CTX decreased in int vs. mu38 (p = 0.006) and mu21 (p = 0.005). Conclusion: The hot bath appears indifferent in relation to osteoporosis, while cold mud-bath shows good effect on bone metabolism. The cold mud-baths help to reduce arthritic inflammation and pain and thereby lead to higher mobility with positive consequence on bone.
- MeSH
- artritida experimentální MeSH
- biomechanika MeSH
- experimenty na zvířatech MeSH
- fraktury femuru MeSH
- kosti a kostní tkáň * metabolismus MeSH
- kostní denzita MeSH
- modely nemocí na zvířatech * MeSH
- osteokalcin MeSH
- osteoporóza MeSH
- potkani Wistar MeSH
- statistika jako téma MeSH
- terapie bahnem MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- práce podpořená grantem MeSH
Atorvastatin belongs to the group of lipid-lowering drugs known as statins. They significantly reduce the levels of total cholesterol, low-density cholesterol and plasma triglycerides therefore they are widely used in the treatment of hypercholesterolemia. Recently developed methods for the determination of atorvastatin and its metabolites in plasma used SPE (solid phase extraction) or LLE (liquid-liquid extraction) as the sample preparation step. However, both procedures are quite time-consuming and need relatively high volume of solvent/sample, which is impractical for the routine analyses of many biological samples. The aim of this work was to develop and validate more suitable sample preparation method for the determination of atorvastatin and its metabolites in biological samples using MEPS (microextraction by packed sorbent). The optimal conditions of MEPS extraction were using C8 sorbent and only 50 μl of the sample. The analytes were eluted by 100 μl of the mixture of acetonitrile:0.1 M ammonium acetate pH 4.5 (95:5, v:v). The analytical method was validated and demonstrated good linearity (r(2)>0.9990), recovery (89-115%) and intra-day precision (RSD<10%). Total time of the sample preparation was three times shorter (7 min) compared to SPE. The volume of sample was twenty times lower and the volume of solvents about ten times lower compared to SPE. Combination of fast MEPS method together with quick UHPLC-MS/MS was used for the determination of atorvastatin and its two metabolites in serum obtained from patients with familiar hypercholesterolemia.
- MeSH
- anticholesteremika izolace a purifikace metabolismus MeSH
- cholesterol krev MeSH
- extrakce na pevné fázi MeSH
- kyseliny heptylové izolace a purifikace metabolismus MeSH
- lidé MeSH
- pyrroly izolace a purifikace metabolismus MeSH
- reprodukovatelnost výsledků MeSH
- statiny izolace a purifikace metabolismus MeSH
- tandemová hmotnostní spektrometrie MeSH
- triglyceridy krev MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- validační studie MeSH
Účel studie: Cílem této pilotní studie bylo popsat změny v lipidovém metabolizmu u pacientů s akutním krvácením do gastrointestinálního traktu (GIT) a posoudit možný vliv hemodiluce a změn v procesu získávání cholesterolu (syntéza a absorpce). Materiál a metody: U dvanácti pacientů s akutním krvácením do GIT byly stanoveny hodnoty lipidového metabolizmu (celkový, LDL a HDL cholesterol, triglyceridy) v den 0, 3 a 6. Ve stejných termínech byly stanoveny hladiny ukazatelů cholesterolové syntézy (skvalen, lathosterol) a absorpce (sitosterol, kampesterol). Výsledky byly hodnoceny srovnáním s kontrolním souborem a porovnáním nemocných s cirhózou a bez postižení jater. Současně byl hodnocen vztah mezi lipidy a hodnotami hemoglobinu, hematokritu a spotřebou transfuzí. Výsledky: Hladiny celkového cholesterolu byly sníženy významně (p < 0,001), HDL a LDL nevýznamně a triglyceridy byly v normě. Hladiny lathosterolu byly sníženy signifikantně (p < 0,05), skvalenu, kampesterolu a sitosterolu nesignifikantně. Porovnání pacientů s cirhózou a bez ní přineslo statisticky významný rozdíl v hladinách cholesterolu a lathosterolu (p < 0,05). Korelace nepřinesly statisticky významné nálezy. Závěr: U pacientů s akutním krvácením do horního GITu byly prokázány změny v metabolizmu lipidů včetně alterace procesu syntézy i absorpce. Hypocholesterolemii proto nelze vysvětlit pouze krevní ztrátou. Je nutné provést další podrobnější studie.
Purpose of the study: The aim of this pilot study was to describe changes in lipid metabolism in patients with acute gastrointestinal (GI) bleeding and to assess possible influence of hemodilution and changes in the cholesterol synthesis/absorption process. Material and methods: In 12 patients with gastrointestinal bleeding, the levels of lipid metabolism (total, LDL and HDL cholesterol and triglycerides) were determined on days 0, 3 and 6. On the same days, levels of the cholesterol synthesis indexes (lathosterol, squalene) and absorption (campesterol, sitosterol) were determined. The results were evaluated in comparison with the control set, and cirrhotic and non-cirrhotic patients were compared. At the same time, correlations of lipids and haemoglobin, hematocrit levels anduse of transfusions were evaluated. Results: The patients had significantly lower levels of total cholesterol (p < 0.001). Decrease of LDL and HDL cholesterol was not significant. Concentrations of triglycerides were normal. Decrease of lathosterol was significant (p < 0.05), but decrease in squalene, campesterol and sitosterol levels was insignificant. Comparing patients with cirrhosis and without cirrhosis showed statistically significant difference in levels of cholesterol and lathosterol (p < 0.05). Correlations did not show any statistically significant findings. Conclusion: In patients with acute GI bleeding, changes is lipid metabolism including alteration of the process of synthesis and absorption were proved. Therefore, hypocholesterolemia cannot be explained by blood loss only. However, more detailed studies need to be carried out. 30. 1. 2013
- MeSH
- akutní nemoc MeSH
- časové faktory MeSH
- cholesterol * analogy a deriváty krev metabolismus MeSH
- fytosteroly krev MeSH
- gastrointestinální krvácení * krev metabolismus MeSH
- HDL-cholesterol krev metabolismus MeSH
- hematokrit MeSH
- hemodiluce MeSH
- jaterní cirhóza komplikace MeSH
- kritický stav MeSH
- LDL-cholesterol krev metabolismus MeSH
- lidé středního věku MeSH
- lidé MeSH
- lipidy MeSH
- pilotní projekty MeSH
- sitosteroly krev MeSH
- skvalen krev MeSH
- statistika jako téma MeSH
- steroly MeSH
- studie případů a kontrol MeSH
- triglyceridy krev metabolismus MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
Micro- and nanostructures prepared from biodegradable homopolymers and amphiphilic block copolymers (AmBCs) have found application as drug-delivery systems (DDSs). The ability to accumulate a drug is a very important parameter characterizing a given DDS. This work focuses on the impact of DDS size, the packing of polymer chains in the DDS, and drug - polymer matrix compatibility on the hydrophobic drug - loading capacity (DLC) of nano/microcarriers prepared from a biodegradable polymer or its copolymer. Using experimental measurements in combination with atomistic molecular dynamics simulations, an analysis of curcumin encapsulation in microspheres (MSs) from polylactide (PLA) homopolymer and nanoparticles (NPs) from PLA-block-poly(2-methacryloyloxyethylphosphorylcholine) AmBC was performed. The results show that curcumin has good affinity for the PLA matrix due to its hydrophobic nature. However, the DLC value is limited by the fact that curcumin only accumulates in the peripheral part of these structures. Such uneven drug distribution in the PLA matrix results from the non-homogeneous density of MSs (non-uniform packing of the polymer chains in the coil). The results also indicate that the MSs can retain a greater amount of hydrophobic drug compared to the NPs, which is associated with the formation of drug aggregates inside the PLA microparticles.
- MeSH
- léčivé přípravky * MeSH
- nanočástice * MeSH
- nosiče léků MeSH
- polyestery MeSH
- polyethylenglykoly MeSH
- velikost částic MeSH
- Publikační typ
- časopisecké články MeSH
The crystal structures of eight cyclodipeptides are determined, incorporating pipecolic acid or proline and phenylalanine or N-methyl phenylalanine. This set of structures allows the evaluation of the effects on molecular conformation and crystal packing of imino acid ring-size, relative configuration of the two amino acids, and N-methylation. In the non-methylated compounds, hydrogen-bonding interactions form one-dimensional motifs that dominate the packing arrangement. Three compounds have more than one symmetry-independent molecule in the asymmetric unit (Z' > 1), indicative of a broad and shallow molecular energy minimum. Density functional theory calculations reveal the interplay between inter- and intramolecular factors in the crystals. Only for the N-methylated compounds do simulations of the molecules in the isolated state succeed to reproduce the observed crystallographic conformations. Puckering of the diketopiperazine ring and the deviation from planarity of the amide bonds are not reproduced in the remaining compounds. Cluster in vacuo calculations with a central cyclodipeptide molecule surrounded by hydrogen-bound molecules establish that hydrogen bonding is of major importance but that other intermolecular interactions must also contribute substantially to the crystal structure. More advanced periodic calculations, incorporating the crystallographic environment to the full extent, are necessary to correctly describe all the conformational features of these cyclodipeptide crystals.
Nylon 6 nanofibers were tested for their ability to serve as a sorbent for solid phase extraction (SPE). The regular nanostructure providing a great sorption area and amidic functionality should lead to the assumption that nylon 6 nanofibers could be used as a novel sorbent with great potential for sample pre-treatment. However, due to the substantial differences between classical particle sorbents used for solid phase extraction and nanofibers, it is necessary to evaluate this novel approach. This article describes three types of laboratory fabricated nylon 6 nanofibers with different surface density (5.04gm-2, 3.90gm-2and 0.75gm-2) and corresponding surface areas for solid phase extraction of several groups of compounds with different structural and physicochemical properties (parabens, steroids, flavonoids and pesticides). The nanofibers were created by needleless electrospinning. Extraction columns were manually packed in classic 1- or 3-mL plastic syringe cartridges with 26-30mg of nanofibers and the column bed was sealed with polypropylene frits. The SPE procedure followed a typical five-step protocol and the collected eluates were analyzed by HPLC with UV detection. Extraction recovery was used as a parameter to evaluate the behavior of the analytes within the SPE process. Under this set condition, the recovery of the SPE process ranged from 23.1% to 125.8%. SPE showed good repeatability (0.58-11.87% RSD) and inter-day reproducibility (3.86-9.79% RSD). The achieved results were compared with SPE using a classic particle sorbent column. Good mechanical and chemical stability of nanofibers was proved. Scanning electron microscope was used for the evaluation of morphological changes in nanostructure. Nylon 6 nanofibers proved being a cost-effective sorbent for repeated use in SPE. Nylon 6 nanofibers have great potential in miniaturized SPE enabling users to overcome troubles with high back-pressure.
- Publikační typ
- časopisecké články MeSH
Invoking the known link between impact sensitivity and compressibility, we have expanded upon an earlier preliminary study of the significance of the available free space per molecule in the unit cell, ΔV. We express ΔV as V(eff) - V(int), where V(eff) corresponds to zero free space, V(eff) = molecular mass/density. V(int) is the intrinsic gas phase molecular volume. We demonstrate that V(int) can be appropriately defined as the volume enclosed by the 0.003 au contour of the molecule's electronic density; this produces packing coefficients that have the range and average value found crystallographically. Measured impact sensitivities show an overall tendency to increase as ΔV becomes larger. For nitramines, the dependence upon ΔV is rather weak; we interpret this as indicating that a single overriding factor dominates their initiation mechanism, e.g., N-NO(2) rupture. (An analogous situation appears to hold for many organic azides.) In addition to the conceptual significance of identifying ΔV as a factor in impact sensitivity, the present results allow rough estimates of relative sensitivities that are not known.
